1. Field of the Invention
The present invention relates to a developing device, a process cartridge, an electrophotographic image forming apparatus and an agitating member. The electrophotographic image forming apparatus serves to form an image on a recording medium by using an electrophotographic image forming process and may include an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer and the like), a facsimile apparatus, a word processor and the like. The process cartridge is constituted by integrally incorporating charging means, or cleaning means, developing means, and an electrophotographic photosensitive member as a cartridge unit which is detachably mountable to a main body of the image forming apparatus, or, by integrally incorporating at least one of charging means and cleaning means, developing means and an electrophotographic photosensitive member as a cartridge unit that is detachably mountable to a main body of the image forming apparatus, or by integrally incorporating developing means and an electrophotographic photosensitive member as a cartridge unit that is detachably mountable to a main body of the image forming apparatus.
2. Related Background Art
In the past, as one of electrophotographic image forming apparatuses, there has been proposed an image forming apparatus to which a developing device or a process cartridge can be detachably mounted. The developing device or the process cartridge comprises a toner container (developer container) for containing toner (developer), and a developing chamber including a developing roller as a developer bearing member. When the developer in the toner container is consumed, the developing device or the process cartridge must be replaced by a new developing device or a new process cartridge. To this end, there is provided a developer-remaining-amount detecting device for detecting a remaining amount of the developer in the toner container.
Such a developer-remaining-amount detecting device has a metallic antenna rod extending in parallel with a longitudinal direction of the developing roller and is disposed in a passage extending from the toner container to the developing roller in the developing chamber. By applying a voltage between the antenna rod and the developing roller to measure the electrostatic capacity therebetween, the toner remaining amount can be detected. When the detected electrostatic capacity is smaller than a predetermined threshold value, it is judged that the toner amount between the antenna rod and the developing roller is small, i.e., the toner amount in the toner container is small. By detecting the change in the electrostatic capacity in this way, the absence of toner has been detected.
However, in the conventional toner-remaining-amount detecting devices, the fact that the remaining toner is little can merely be known immediately before the toner is used up, but, the user cannot know how much toner is remaining in the toner container.